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P219A diagnostic techniques

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12 May 2019 20:03 #29577 by Tyler
P219A diagnostic techniques was created by Tyler
Looking for any ideas or speculation the community can offer. :cheer: FYI, this car is fixed and down the road. This one took more time and money to fix than it should've, so I'm looking for ways to improve my process for the next time.

2012 Terrain, LEA (2.4L) engine is setting a P219A Air/Fuel Ratio Imbalance Bank 1 and a P0300. Previous tech did plugs, intake gaskets and clean the PCV passage, cleaned the MAF, and ran two induction services. Code resets.

I get it and immediately note the misfire at cold idle. Counts up on #1 and resets P0300 almost immediately. Classic carboned intake valves, and the borescope confirms. Induction services aren't cutting it on this one. I get the OK to pull the intake again and manually clean the valves. I also run the Automated Injector Balance test a few times, and don't see an obvious issue. The spread between the injectors is typical of what I see on known good LEA engines.

Valves are clean, cold miss is gone, but P219A resets on the highway. :angry: Trims are around +7% total when the code sets, and no cylinder is counting misses. I go over all my testing again, including the injector balance - still looks good. It's down to a injector issue (that I can't prove), or a tiny crack in the exhaust manifold (that I've seen tons of times and never causes a P219A). We go for the injectors anyway.

After the injectors are installed, I get the P219A monitor to run and pass. :woohoo: I redo the injector balance test at this time, expecting a night and day difference. Nope! :silly: None of the old injector tips were dirty, and a fuel sample taken before replacement was clean.

So, my question is, how could I have positively ID'd an injector issue sooner? Just working down the list of suspects seems inefficient and costly to me. :( I use to have SOME faith in the Automated Injector Balance test. Now I have serious doubts.

What say you? :cheer:

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12 May 2019 21:57 #29582 by Chad
Replied by Chad on topic P219A diagnostic techniques
I wonder if the First Look Sensor on the fuel rail would show something.


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"Understanding a question is half an answer."

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15 May 2019 08:21 - 15 May 2019 10:48 #29659 by Tyler
Replied by Tyler on topic P219A diagnostic techniques
I always wanted one of those! :cheer: But I don't think it would have worked? Being GDI, I'm not sure where I'd hook it in. I know GM has their AFIT tester for this exact issue, but new ones are $3K. :(

Also ran the same Automated Injector Balance test on a '13 Equinox with no engine performance issues, and it gave similar results to the problem car. At this point, I have almost no faith in the automated test. :lol:
Last edit: 15 May 2019 10:48 by Tyler.

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15 May 2019 11:06 #29666 by Tyler
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Going back over my data, hoping I missed something.

Problem vehicle before injector replacement:



Problem vehicle after injectors:



Known good vehicle:

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15 May 2019 11:26 #29667 by Chad
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I don't see it. The biggest spread is after the repair. :blink:

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15 May 2019 15:10 #29679 by PDM
Replied by PDM on topic P219A diagnostic techniques
In the "known good" and "after", the Pressure Drop values are all numerically higher than Rail Pressure. In the "before", the Pressure Drop values are all numerically lower than Rail Pressure. If this is of any significance, also note that the numerical difference between Pressure Drop and Rail Pressure on the "after" (new injectors) is greater than on "known good" (used injectors)
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15 May 2019 15:14 #29680 by PDM
Replied by PDM on topic P219A diagnostic techniques
Also, why the difference in rail pressure between before and after? I have no idea about how this test works. I'm just looking at the numbers.

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15 May 2019 16:20 #29683 by Chad
Replied by Chad on topic P219A diagnostic techniques

PDM wrote: Also, why the difference in rail pressure between before and after?


Good question. :)

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16 May 2019 11:34 #29710 by Tyler
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PDM wrote: Also, why the difference in rail pressure between before and after? I have no idea about how this test works. I'm just looking at the numbers.


Sorry, the pictures that I posted don't represent the test very well. :blush: Here's the graphed data of the PIDs provided while the test is running. The PIDs you can look at while the test is running are fixed and cannot be changed (on the Snap-On, anyway).

www.scanshare.io/share/JsRrT38rsEuE9GUX1aaogw



Without having a scope on the injectors and the high pressure fuel pump solenoid, I can't say EXACTLY what the PCM is doing during this test.
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16 May 2019 12:14 #29714 by PDM
Replied by PDM on topic P219A diagnostic techniques
Do you have a shot like that for "before"? You could probably see a sluggish injector with that
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16 May 2019 18:10 #29727 by Tyler
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PDM wrote: Do you have a shot like that for "before"? You could probably see a sluggish injector with that


I'll dig it up! I have a tendency to hit 'Save' on just about everything I think might be relevant/interesting, but struggle to find what I'm looking for later. :silly:

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16 May 2019 18:22 #29728 by Tyler
Replied by Tyler on topic P219A diagnostic techniques
Found it. This was taken before any repairs were performed.



Something I've noted about the way the Snappy runs this test - it keeps a history of the results of the last test, if you run the test multiple times per key cycle. You can see this in the graphs, especially injector #4. The previous test showed 59.4 PSI, but the latest test shows 68.4 PSI. The two tests were run seconds apart, so it's not like fuel temperature or engine conditions changed a lot in between. :dry:

I'm really tempted to pay for a GM subscription so I can compare the Snap-On to the GDS2, and maybe the Launch and Autel if I have time. Maybe this is a decent test? It just doesn't get implemented well by Snap-On.
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16 May 2019 20:46 #29736 by Ben
Replied by Ben on topic P219A diagnostic techniques
I have had no luck with snapon's automated test either I've had tons of the Chevy 6.0's with plugged injectors pass that test with flying colors...

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16 May 2019 21:16 #29737 by PDM
Replied by PDM on topic P219A diagnostic techniques
Wow. I was hoping for something, but that really doesn’t tell you anything

Looks like it doesn’t have the resolution you need either.

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17 May 2019 20:21 #29761 by Tyler
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Ben wrote: I have had no luck with snapon's automated test either I've had tons of the Chevy 6.0's with plugged injectors pass that test with flying colors...


Thanks for responding. B) The only 6.0 I've had with a suspected injector issue went to the dealer begging for goodwill, so I didn't get to see the result.

Wow. I was hoping for something, but that really doesn’t tell you anything

Looks like it doesn’t have the resolution you need either.


:lol: Yep! I got a hold of yet another '13 Equinox today, separate from all the others I've posted so far. Ran it's injector test - results were similarly inconclusive.

Also ran the same test on the Autel. Aside from displaying the results in kPa instead of PSI, the test results are largely the same.

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26 Jun 2019 12:22 #31059 by Tyler
Replied by Tyler on topic P219A diagnostic techniques
Update! Doesn't directly pertain to the P219A code, but more GM GDI injectors in general.

'15 Silverado 5.3L has a recurring P050D Cold Start Rough Idle. Has a mostly dead misfire on #3 for about 30 seconds. Smooth otherwise. Here's a before of the Automated waste-of-your-time Injector Test.



After pulling the intake once to clean intake valves and a lot of testing, I get the go ahead to replace #1 and #3 injectors. Here's the automated test afterwards:



What a useless test. :silly:

Side note, I'm very happy with the test I came up with to pin this one down. :cheer: Put the Pico TA204 secondary probe on the #3 plug wire, and put the AESWave Paddle Probe on the #2 plug wire (which never missed). During a cold start, engine missing away, I saw this on #2:



Textbook waveform. #3 showed this:



Lookin' lean. B) Secondary ignition FTW.
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26 Jun 2019 12:31 #31060 by PDM
Replied by PDM on topic P219A diagnostic techniques

Tyler wrote: What a useless test. :silly:

Secondary ignition FTW.


TRUTH

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